CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Common Stock In Treasury	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Total
Balance at Dec. 31, 2018	$ 535	$ (1,461,002)	$ 1,326,645	$ 1,419,449	$ (324)	$ 1,285,303
Balance (in shares) at Dec. 31, 2018	53,536,000	(29,601,000)
Increase (Decrease) in Stockholders' Equity
Stock compensation expense			9,607			9,607
Exercise of stock options	$ 1		2,044			2,045
Exercise of stock options (in shares)	41,000
Issuance of equity	$ 1		(447)			(446)
Issuance of equity (in shares)	118,000
Repurchase of stock		$ (3,725)				(3,725)
Repurchase of stock (in shares)		(61,000)
Net income				431		431
Other comprehensive income (loss)-other					320	320
Adoption of ASC				(145)		(145)
Balance at Mar. 31, 2019	$ 537	$ (1,464,727)	1,337,849	1,419,735	(4)	1,293,390
Balance (in shares) at Mar. 31, 2019	53,695,000	(29,662,000)
Balance at Dec. 31, 2019	$ 543	$ (1,464,727)	1,386,616	1,475,207	144	$ 1,397,783
Balance (in shares) at Dec. 31, 2019	54,285,000	(29,662,000)				24,623,000
Increase (Decrease) in Stockholders' Equity
Stock compensation expense			6,057			$ 6,057
Exercise of stock options	$ 2		11,261			$ 11,263
Exercise of stock options (in shares)	216,000					216,734
Issuance of equity	$ 1		(1,137)			$ (1,136)
Issuance of equity (in shares)	130,000
Net income				18,250		18,250
Other comprehensive income (loss)-other					(201)	(201)
Adoption of ASC				(413)		(413)
Balance at Mar. 31, 2020	$ 546	$ (1,464,727)	$ 1,402,797	$ 1,493,044	$ (57)	$ 1,431,603
Balance (in shares) at Mar. 31, 2020	54,631,000	(29,662,000)				24,969,000